[WK2][EFL] WebView: Add callbacks to the WKViewClient to remove direct access to page viewport controller
https://bugs.webkit.org/show_bug.cgi?id=110741

Reviewed by Anders Carlsson.

Provided WKViewClient with didRequestScroll, didRenderFrame and didCompletePageTransition
callbacks so that direct access from WebView to page viewport controller is avoided.

Implementation of callbacks is also added to keep the current EFL WK2 functionality.

* UIProcess/API/C/efl/WKView.h:
* UIProcess/efl/PageLoadClientEfl.cpp:
(WebKit::PageLoadClientEfl::didCommitLoadForFrame):

    Moved here code from deleted WebView::didCommitLoad.

* UIProcess/efl/ViewClientEfl.cpp:
(WebKit::ViewClientEfl::didChangeContentsPosition):
(WebKit):
(WebKit::ViewClientEfl::didRenderFrame):
(WebKit::ViewClientEfl::didCompletePageTransition):
(WebKit::ViewClientEfl::ViewClientEfl):
* UIProcess/efl/ViewClientEfl.h:
(ViewClientEfl):
* UIProcess/efl/WebView.cpp:
(WebKit::WebView::pageDidRequestScroll):
(WebKit::WebView::didRenderFrame):
(WebKit::WebView::pageTransitionViewportReady):
* UIProcess/efl/WebViewClient.cpp:
(WebKit::WebViewClient::didChangeContentsPosition):
(WebKit):
(WebKit::WebViewClient::didRenderFrame):
(WebKit::WebViewClient::didCompletePageTransition):
* UIProcess/efl/WebViewClient.h:
(WebCore):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147913 268f45cc-cd09-0410-ab3c-d52691b4dbfc